Zephyr Teachout, standing near Trump Tower on 5th Avenue, launched her campaign as a candidate for New York State Attorney General on June 5, 2018. (Andrew Savulich / NEW YORK DAILY NEWS)

The lawyer who successfully argued before the U.S. Supreme Court to overturn the Defense of Marriage Act is endorsing Fordham Law Prof. Zephyr Teachout for state attorney general, the Daily News has learned.

Roberta Kaplan plans to make the announcement during a conference call with Teachout Friday to discuss the retirement of Supreme Court Justice Anthony Kennedy.

“Now, more than ever, as our nation faces imminent threats to our democratic system and the potential reversal of long-established fundamental rights for women, minorities, immigrants and LGBTQ Americans, it would be hard to overstate the importance of having an Attorney General with courage, deep knowledge of constitutional law, and a demonstrated commitment to integrity and independence,” Kaplan said in backing Teachout.

She added that “Zephyr, who has made it clear that she is 100% committed to being the Attorney General and does not see the job as a mere stepping stone to higher office, is clearly the best-qualified candidate to meet these unprecedented challenges head on.”

Teachout—one of four Democrats seeking to run in the Sept. 13 Democratic primary for attorney general — called Kaplan “a total icon to me and so many other for not just her brilliance, but her leadership in law.”

“She’s a lawyer’s lawyer and she really understands the importance of this office in standing up to Trump and the Trump administration’s persistent unconstitutional actions,” Teachout said.

Kaplan is best known for representing gay marriage pioneer Edith Windsor in a case before the Supreme Court.

With gay marriage still illegal in the United States, Windsor in 2007 traveled to Toronto to wed Thea Spyer, who died two years later. Windsor, who was the sole heir to Syper’s estate, sued when she was hit with taxes she would have avoided had she married a man.

With Kaplan arguing on her behalf, the U.S. Supreme Court in 2013 ruled in Windsor’s favor, striking down the federal Defense of Marriage Act that refused to recognize same-sex unions.

In addition to Teachout, New York City Public Advocate Letitia James, who is automatically on the primary ballot after winning more than 85% of the delegate vote at the May state Democratic convention, former Gov. Cuomo and Hillary Clinton aide Leecia Eve, and Hudson Valley Rep. Sean Patrick Maloney have also announced they are running for state attorney general as Democrats.